Joy Villa at the Grammy Awards in February. She accused Corey Lewandowski, President Trump’s former campaign manager, of slapping her buttocks “violently hard, enough to hurt me,” at a party last month.CreditCreditJordan Strauss/Invision, via Associated Press

A pop singer filed a police report this week accusing Corey Lewandowski, President Trump’s former campaign manager, of slapping her twice on the buttocks at a party in Washington in November.

In a phone interview on Wednesday, the singer, Joy Villa, 31, said she met Mr. Lewandowski for the first time at a party at the Trump International Hotel on Nov. 28 celebrating Mr. Trump’s election the previous year, and the two took a photograph together.

After that, Mr. Lewandowski slapped her “violently hard, enough to hurt me,” she said, adding that she told him to stop, and that she could report him for sexual harassment.

“He says, ‘Go ahead, I work in the private sector,’” Ms. Villa said. “He laughs at me and then he does it again, extra hard this time, just to show me that he wasn’t afraid. At that point I was so paralyzed by fear. I was very shocked, and my friend grabbed me and pulled me away from him.”

Citing her respect for Mr. Lewandowski’s work on the Trump campaign and her fear of bringing shame to his family, Ms. Villa said she did not decide to file a report with the Metropolitan Police Department until she was approached by a reporter at Politico this month. Then, she said, she decided to speak publicly about the episode with the support of her friends and family.

The Metropolitan Police Department confirmed on Wednesday that a sexual assault allegation report matching a case number that Ms. Villa provided was filed on Sunday. “It remains under investigation, and nobody has been charged,” Sean Hickman, a spokesman for the Police Department, said in an email.

Mr. Lewandowski did not respond to voice mail or text messages on Wednesday seeking comment.

Ms. Villa said she was considering running for Congress in Florida, where she lives. She is being advised by Roger J. Stone Jr., a staunch supporter of Mr. Trump who has clashed with Mr. Lewandowski. Mr. Stone did not immediately respond to an email seeking comment on Wednesday.

Ms. Villa is a singer and songwriter known for her support for Mr. Trump. She wore a dress bearing his campaign slogan, “Make America Great Again,” to the Grammy Awards in February. After that, her album, “I Make the Static,” made the top 15 of the Billboard 200 chart.

In recent months, sexual harassment allegations have led to resignations across a wide range of industries including entertainment, journalism and technology. Several politicians have also said they will step down or not seek re-election in the face of harassment allegations this month, including Senator Al Franken and United States Representatives Trent Franks, Blake Farenthold and John Conyers Jr. The president, too, has faced allegations of sexual assault and harassment. Ms. Villa said she still supported Mr. Trump.

“This has nothing to do with politics,” she said of the report she filed against Mr. Lewandowski. “This has everything to do with human decency.”